Apple later issued a more formal statement in response to growing media reports of reception problems, saying: "Gripping any phone will result in some attenuation of its antenna performance, with certain places being worse than others depending on the placement of the antennas. This is a fact of life for every wireless phone. If you ever experience this on your iPhone 4, avoid gripping it in the lower left corner in a way that covers both sides of the black strip in the metal band, or simply use one of many available cases."

Now, popular review site Consumer Reports is confirming the iPhone 4 does suffer from a defect that can affect reception.

"Consumer Reports' engineers have just completed testing the iPhone 4, and have confirmed that there is a problem with its reception," the publication states in a new blog post. "When your finger or hand touches a spot on the phone's lower left side—an easy thing, especially for lefties—the signal can significantly degrade enough to cause you to lose your connection altogether if you're in an area with a weak signal. Due to this problem, we can't recommend the iPhone 4."

Consumer Reports says it tested three iPhone 4 devices purchased from three separate retailers in New York. In a controlled environment not susceptible to outside interference from radio signals, Consumer Reports says the iPhone 3GS and Palm Pre did not suffer from signal-loss problems affecting the iPhone 4.

"Our findings call into question the recent claim by Apple that the iPhone 4's signal-strength issues were largely an optical illusion caused by faulty software that 'mistakenly displays 2 more bars than it should for a given signal strength'," Consumer Reports writes.

Consumer Reports testing also indicated AT&T's network may not be the primary suspect for reception problems.

The signal issue is the reason Consumer Reports does not give a "recommended" rating for the iPhone 4. To fix the issue, the publication says, users need to cover the antenna gap with a piece of duct tape.

"Apple needs to come up with a permanent—and free—fix for the antenna problem before we can recommend the iPhone 4," Consumer Reports says.